The present invention relates generally to semiconductor fabrication and, more particularly, to methods for reducing slurry usage in a linear chemical mechanical planarization (CMP) system.
In the fabrication of semiconductor devices, CMP is used to planarize globally the surface of an entire semiconductor wafer. CMP is often used to planarize dielectric layers as well as metallization layers. As is well known to those skilled in the art, in a CMP operation a wafer is rotated under pressure against a polishing pad in the presence of a slurry.
In conventional linear CMP systems, a slurry manifold, which is sometimes referred to as a slurry bar, dispenses slurry onto the polishing pad, which is in the form of a belt. In one known linear CMP system, the slurry manifold includes multiple, e.g., six, nozzles, each of which is disposed about 6 inches above the top surface of the polishing pad. In operation, each of the multiple nozzles continuously dispenses slurry droplets onto the top surface of the polishing pad.
The continuous dispensing of slurry in linear CMP systems is problematic because the slurry is relatively expensive. Indeed, it has been estimated that the cost of the slurry accounts for roughly 30% of the total cost of the consumables used in linear CMP systems. As such, any excess slurry that is used significantly increases the cost of ownership associated with linear CMP systems.
In view of the foregoing, there is a need for a method of dispensing slurry in a linear CMP system that reduces the amount of slurry used and thereby reduces the cost of ownership associated with linear CMP systems.